在不更改POJO的情况下向REST端点提供多态反序列化/序列化参数 [英] Supply Polymorphic De-serialization/Serialization parameters to REST endpoint without changing POJOs

问题描述

我正在处理JAX-RS应用程序，其中端点使用和产生JSON类型数据.为此，我正在使用Jackson.

I am working on a JAX-RS application, where endpoints Consume and Produce JSON type data. And I am using Jackson for that purpose.

据我所知，处理Jackson中多态行为的方法之一是在POJO上使用@JsonTypeInfo和@JsonSubTypes.

As I know one of the ways to handle Polymorphic behavior in Jackson is to use @JsonTypeInfo and @JsonSubTypes on POJOs.

但是在我的情况下，POJO并不是代码的一部分，它们嵌入在JAR文件中，我无法对其进行编辑.

But in my case POJOs are not part of code, they're embedded in a JAR file and I can't edit them.

有什么方法可以在没有POJO注释的情况下在外部将此信息指定为Jackson吗?

Is there any way where I can specify this info to Jackson externally without POJO annotations ?

请为我指出正确的方向，前面已经讨论过.

Please point me to the right direction of this has already been discussed earlier.

推荐答案

有什么办法可以在没有POJO注释的情况下向外部Jackson指定此信息?

Is there any way where I can specify this info to Jackson externally without POJO annotations?

如果考虑使用混合注释，

使用注释仍然是一种有效的方法.

Using annotations is still a valid approach if you consider mix-in annotations.

如果不能修改源代码，则可以使用混合注释添加

When modifying the source code is not an option, you can use mix-in annotations to add Jackson annotations to a bean. You can think of it as kind of aspect-oriented way of adding more annotations during runtime, to augment statically defined ones.

首先定义一个混合注释接口或类:

First define a mix-in annotation interface or class:

@JsonTypeInfo(use = Id.CLASS, include = As.PROPERTY, property = "class")
public interface FooMixIn {

}

然后配置ObjectMapper以将定义的接口用作POJO的混合项:

Then configure ObjectMapper to use the defined interface as a mix-in for your POJO:

ObjectMapper mapper = new ObjectMapper().addMixIn(Foo.class, FooMixIn.class); 

可以混入Jackson识别的所有注释集.有关更多详细信息，请查看Jackson 文档.

All annotation sets that Jackson recognizes can be mixed in. For more details, have a look at the Jackson documentation.

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